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‣ TBX22 Missense Mutations Found in Patients with X-Linked Cleft Palate Affect DNA Binding, Sumoylation, and Transcriptional Repression

Andreou, Artemisia M. ; Pauws, Erwin ; Jones, Marius C. ; Singh, Manvendra K. ; Bussen, Markus ; Doudney, Kit ; Moore, Gudrun E. ; Kispert, Andreas ; Brosens, Jan J. ; Stanier, Philip 
Fonte: American Society of Human Genetics Publicador: American Society of Human Genetics
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
The T-box transcription factor TBX22 is essential for normal craniofacial development, as demonstrated by the finding of nonsense, frameshift, splice-site, or missense mutations in patients with X-linked cleft palate (CPX) and ankyloglossia. To better understand the function of TBX22, we studied 10 different naturally occurring missense mutations that are phenotypically equivalent to loss-of-function alleles. Since all missense mutations are located in the DNA-binding T-box domain, we first investigated the preferred recognition sequence for TBX22. Typical of T-box proteins, the resulting sequence is a palindrome based around near-perfect copies of AGGTGTGA. DNA-binding assays indicate that missense mutations at or near predicted contact points with the DNA backbone compromise stable DNA-protein interactions. We show that TBX22 functions as a transcriptional repressor and that TBX22 missense mutations result in impaired repression activity. No effect on nuclear localization of TBX22 was observed. We find that TBX22 is a target for the small ubiquitin-like modifier SUMO-1 and that this modification is required for TBX22 repressor activity. Although the site of SUMO attachment at the lysine at position 63 is upstream of the T-box domain...